It is known that an aircraft, in particular a transport airplane, comprises a number of computers that are intended to facilitate (or handle) the management of certain piloting, navigation and/or surveillance tasks, and the use, to implement at least some of their functions, geographical data. Typical of these are a flight management system of FMS (Flight Management System) type, an airport navigation system of OANS (Onboard Airport Navigation System) type, and an environment surveillance system of AESS (Aircraft Environment Surveillance System) type.
For this, these various systems each comprise or are each associated with a geographical database. Thus, a system of OANS type comprises a database containing at least airport mapping information, and a system of AESS type comprises a database containing at least information relating to the relief of the terrain. FR-2 884 020 and FR-2 883 964 disclose an airport navigation aid device.
It is known that such onboard systems, that use geographical data, such as a flight management system for example, often comprise a dedicated protocol with a proprietary format, that enables them to effectively manage the interface between the core of the system and an associated geographical database, namely a navigation database in the case of a flight management system of FMS type. This protocol is locally optimized for a system so as to minimize the response time following an external request, upon a request from a pilot via an interface of the FMS system for example.
In a standard architecture, each onboard system that uses geographical data comprises its own geographical database. Also, each system locally optimizes its use so that the aircraft includes as many different protocols. This is why, if a new system needs a first geographical datum that is contained in the database of a first system, it must subscribe to this first system and must acquire this first datum through it. This first datum therefore passes via the dedicated protocol to said first system before arriving at this new system. If this new system then needs a second geographical datum that is stored in the database of a second system, this second datum must pass via the dedicated protocol to said second system before arriving at said new system. As a result, the data pass through different protocols and different systems.
Such a standard architecture, in which a protocol is associated with each database that forms part of a system, has numerous drawbacks. In particular:                the deliveries to a user system of different geographical data can originate from different systems for one and the same geographical region. These deliveries are neither synchronized nor organized, which can provoke, for example, transient displays on a screen of the cockpit, relating to partial geographical information. As an example, the geographical data (waypoint, radio beacon, etc.) that are stored in the database of the FMS system may be displayed on a navigation screen, while the associated geographical data (terrain, obstacle, weather) that are stored in the database of the AESS system are not yet displayed;        the use of the geographical data is not optimized. The different systems comprise geographical databases that often concern all of the terrestrial globe and that therefore require memories of large size, whereas, for a given flight, the user systems of the aircraft require only a portion of these stored geographical data. Thus, the risks of corruption of the geographical data are multiplied and diversified; and        the geographical data pass through different protocols, which increases the complexity of their use and reduces the possibilities of changing the use of geographical data on board the aircraft. In particular, a new user system must, generally, observe different protocols to collect the geographical data that it needs.        